Various medical devices and methods are used for percutaneous drug delivery or extraction of biologic material from the intervertebral disc. In general, most current methods for injecting therapeutics into the intervertebral disc have the drawback that some material leaks out of the disc during the procedure. Moreover, the insertion of a drug delivery needle through the annulus can weaken it, thereby making it more susceptible to rupturing. Furthermore, if the patient needs repeated dosing, multiple needle insertions can result in a plurality of punctures, and progressive weakening of the annulus. A single percutaneous insertion capable of repeated dosing without any perforation of the annulus would provide a more flexible and potentially safer method of therapy delivery.